The present invention relates to a system and method for controlling an engine including an idle shutdown feature.
Diesel engines have a wide variety of applications including passenger vehicles, marine vessels, earth-moving and construction equipment, stationary generators, and on-highway trucks, among others. Electronic engine controllers provide a wide range of flexibility in tailoring engine performance to a particular application without significant changes to engine hardware. While diesel fuel is often less expensive, and diesel engines are more efficient than gasoline powered engines, diesel engine applications often require running the engine continuously over long periods of time.
In many diesel engine applications, the engine operator does not own the engine and therefore does not pay for the fuel or engine maintenance. The operator often seeks maximum power whereas the owner strives to achieve maximum fuel economy. To further improve fuel efficiency, manufacturers have developed and implemented various electronic engine control features which attempt to optimize fuel economy while maintaining acceptable (although often not maximum) power for the particular application and operating conditions. Furthermore, features have been provided which allow the engine owner to impose operational limits on the engine operator to promote safety and/or fuel economy. As such, operators may tamper with the engine sensors or actuators to xe2x80x9ctrickxe2x80x9d the engine controller and circumvent or defeat various engine control features designed to improve fuel economy so the operator can obtain more power or speed, or keep the engine running.
Idle shutdown is an electronic engine control feature designed to prevent unnecessary engine idling with resulting lower fuel economy. On-highway truck drivers often leave the engine idling for extended periods of time for various reasons such as avoiding difficulty in restarting the engine or keeping the vehicle warm, for example. In one implementation of an idle shutdown feature, when the engine controller determines that the vehicle is parked and the engine has been idling for some period of time, the engine controller automatically stops the engine. The idle shutdown includes an automatic override feature to prevent the engine from being automatically stopped when the engine is being used to drive auxiliary equipment in power take-off (PTO) mode. For example, the engine may be running a generator to cool a refrigerated truck, driving a pump on a fire engine, powering hydraulics for a crane or construction equipment, etc. As such, drivers may xe2x80x9ctrickxe2x80x9d the engine controller by placing the engine in a mode, such as PTO mode, which automatically overrides the idle shutdown feature even though the engine is not actually being used to drive any auxiliary equipment.
The present invention includes a method for controlling a compression ignition engine having an electronic control module with an idle shutdown feature to automatically stop the engine after idling for a period of time. The method includes determining whether the engine is being loaded and overriding the idle shutdown feature to keep the engine running when the engine is being loaded. In one embodiment of the present invention, the engine controller determines whether the current operating conditions are consistent with an operator selected operating mode, such as PTO, to determine whether to override the idle shutdown feature and keep the engine running.
The present invention is implemented in an embodiment which controls a compression ignition internal combustion engine installed in a vehicle to reduce unnecessary idling. The engine controller monitors operating conditions to determine that the vehicle is stationary, monitors the engine to determine the engine is idling, initiates a timer/counter to provide an indication of engine idling time, determines that the engine is operating in an auxiliary power mode, determines engine load, and automatically stops the engine when the idling time exceeds a first threshold and the engine load is less than a second threshold.
The present invention includes a number of advantages relative to prior art idle shutdown features. For example, the present invention provides an idle shutdown feature with automatic override which is less susceptible to improper use by engine operators and should therefore result in improved fuel economy in certain circumstances. The present invention automatically determines whether the engine operating conditions are consistent with a special operating mode, such as PTO, to enable the automatic idle shutdown override. In one embodiment, the present invention provides a system and method for determining the current engine load prior to overriding the idle shutdown feature so that the engine is not unintentionally shutdown. The present invention makes it more difficult for operators to defeat the idle shutdown feature and keep the engine running by selecting an operating mode, such as PTO, which would otherwise override the idle shutdown feature, unless the engine operating conditions indicate the mode selection is proper. Increased use of the idle shutdown feature by detecting attempts to defeat it may have many additional benefits associated with the reduction in unnecessary idling, such as reduced engine wear, reduced emissions, and reduced maintenance requirements such as oil changes and the like.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.